U.S. patent number 8,307,626 [Application Number 12/393,743] was granted by the patent office on 2012-11-13 for auxiliary pump system for fan drive gear system.
This patent grant is currently assigned to United Technologies Corporation. Invention is credited to William G. Sheridan.
United States Patent |
8,307,626 |
Sheridan |
November 13, 2012 |
Auxiliary pump system for fan drive gear system
Abstract
A pump system for lubricating a bearing in a gear system
includes an auxiliary pump connected to the gear system. The
auxiliary pump is fluidically connected to the bearing through an
auxiliary supply passage and to a reservoir through an auxiliary
scavenge passage. An auxiliary valve is fluidically connected to
the auxiliary supply passage for transferring liquid from the
auxiliary pump to the bearing when a pressure in the auxiliary
supply passage downstream of the auxiliary valve is less than a
particular threshold and for transferring liquid from the auxiliary
pump to the reservoir when the pressure in the auxiliary supply
passage downstream of the auxiliary valve is greater than the
particular threshold. A method for circulating liquid is also
included.
Inventors: |
Sheridan; William G.
(Southington, CT) |
Assignee: |
United Technologies Corporation
(Hartford, CT)
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Family
ID: |
41667246 |
Appl.
No.: |
12/393,743 |
Filed: |
February 26, 2009 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20100212281 A1 |
Aug 26, 2010 |
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Current U.S.
Class: |
60/39.08;
415/110; 415/111; 184/29; 60/802; 415/112; 184/26; 184/27.2;
60/772 |
Current CPC
Class: |
F01D
25/20 (20130101); F02C 7/36 (20130101); F01M
2001/123 (20130101) |
Current International
Class: |
F02C
7/06 (20060101) |
Field of
Search: |
;60/226.1,772,39.08,802
;184/26,6.11,27.2,29 ;137/119.01,118.01 ;415/110-113 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1925856 |
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May 2008 |
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EP |
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2673676 |
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Sep 1992 |
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FR |
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8270428 |
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Oct 1996 |
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JP |
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Other References
Extended European Search Report in foreign counterpart Application
No. 09252941.1, dated Nov. 22, 2011. cited by other.
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Primary Examiner: Gartenberg; Ehud
Assistant Examiner: Sutherland; Steven
Attorney, Agent or Firm: Kinney & Lange, P.A.
Claims
The invention claimed is:
1. A pump system for lubricating a bearing in a gear system of a
gas turbine, the pump system comprising: a main pump fluidically
connected to the bearing through a main supply passage; an
auxiliary pump mechanically connected to the gear system, wherein
the auxiliary pump is fluidically connected to the bearing through
an auxiliary supply passage and to a reservoir through an auxiliary
scavenge passage; an auxiliary valve fluidically connected to the
auxiliary supply passage, for transferring liquid from the
auxiliary pump to the bearing when a pressure in the auxiliary
supply passage downstream of the auxiliary valve is less than a
particular threshold, and for transferring liquid from the
auxiliary pump to the reservoir when the pressure in the auxiliary
supply passage downstream of the auxiliary valve is greater than
the particular threshold; and a compartment wall defining a
compartment cavity, wherein the reservoir is positioned at a bottom
of the compartment cavity, wherein a portion of the compartment
wall defines the reservoir, and wherein the compartment cavity
contains the auxiliary pump, the auxiliary valve, and the
bearing.
2. The pump system of claim 1, and further comprising: a manifold
connected to the main supply passage between the main pump and the
bearing and connected to the auxiliary supply passage between the
auxiliary valve and the bearing; and a main reservoir which is
different from the reservoir, which is connected to the main pump
through a main supply passage, and which is connected to the
reservoir through a main scavenge passage.
3. The pump system of claim 2, wherein the auxiliary valve
comprises: a valve body defining a valve cavity; a manifold port in
the valve body, the manifold port fluidically connecting the valve
cavity to the manifold; a reservoir port in the valve body, the
reservoir port fluidically connecting the valve cavity to the
reservoir; an auxiliary pump port in the valve body, the auxiliary
pump port fluidically connecting the valve cavity to the auxiliary
pump; and a valve stem comprising a first end and a second end, the
first end connected to a manifold disc and the second end connected
to a reservoir disc, wherein the valve stem passes through the
manifold port, the valve cavity, and the reservoir port, wherein
the manifold disc is sized to close the manifold port, the
reservoir disc is sized to close the reservoir port, and the valve
stem is sized to allow liquid flow through the reservoir port when
the manifold port is closed by the manifold disc.
4. The pump system of claim 3, wherein the auxiliary valve further
comprises: a spring for applying a force on the valve stem, biasing
the valve stem toward a position where the manifold disc does not
close the manifold port.
5. The pump system of claim 3, wherein the manifold port has a
greater flow area than the reservoir port.
6. The pump system of claim 1, and further comprising: a main
scavenge passage fluidically connecting the main pump to the
reservoir, wherein the main scavenge passage has a main scavenge
inlet positioned in the reservoir and the auxiliary scavenge
passage has an auxiliary scavenge inlet positioned in the
reservoir, wherein the reservoir has a reservoir bottom, and
wherein the auxiliary scavenge inlet is oriented closer to the
reservoir bottom than the main scavenge inlet is to the reservoir
bottom.
7. The pump system of claim 1, wherein the gear system comprises a
fan drive gear system connecting a fan shaft to a low pressure
spool in a gas turbine engine.
8. The pump system of claim 7, wherein the main pump is connected
through gearing to a high pressure spool.
9. A gas turbine engine comprising: a spool comprising a compressor
fixedly connected to a turbine via a spool shaft; a fan drive gear
system that includes a bearing; a fan shaft connected through the
fan drive gear system to the spool; a reservoir for holding liquid;
and an auxiliary pump system comprising: an auxiliary pump
mechanically connected to the fan drive gear system and fluidically
connected to the reservoir; and a valve, fluidically connected to
the auxiliary pump via a first passage and to the bearing via a
second passage, the valve comprising: a valve body defining a valve
cavity; a first, second, and third port in the valve body; a valve
member with a first position and a second position relative to the
valve body, wherein the auxiliary pump is fluidically connected to
the bearing through the first and second ports when the valve
member is in the first position and wherein the auxiliary pump is
fluidically connected to the reservoir through the first and third
ports when the valve member is in the second position; and a
compartment wall defining a compartment cavity, wherein the
reservoir is positioned at a bottom of the compartment cavity,
wherein a portion of the compartment wall defines the reservoir,
and wherein the compartment cavity contains the auxiliary pump, the
valve, and the bearing.
10. The gas turbine engine of claim 9, wherein the auxiliary pump
system further comprises: a manifold fluidically connected to the
second passage between the valve and the bearing.
11. The gas turbine engine of claim 10, wherein the valve member
comprises: a valve stem comprising a first end and a second end,
the first end connected to a manifold disc and the second end
connected to a reservoir disc, wherein the valve stem passes
through the second port, the valve cavity, and the third port,
wherein the manifold disc is sized to close the second port, the
reservoir disc is sized to close the third port, and the valve stem
is sized to allow liquid flow through the third port when the
second port is closed by the manifold disc.
12. The gas turbine engine of claim 10, wherein the valve further
comprises: a spring for applying a force on the valve member,
biasing the valve member toward the first position.
13. The gas turbine engine of claim 10, wherein the second port has
a greater flow area than the third port.
14. A method for circulating liquid in a gas turbine engine, the
method comprising: driving a main pump via a high pressure spool
operably coupled to the main pump; pumping a lubricating liquid
with the main pump from a main reservoir to a bearing, collecting
the lubricating liquid in a collection reservoir which is different
than the main reservoir after use by the bearing, and transferring
the lubricating liquid from the collection reservoir back to the
main reservoir, when a high pressure spool is rotating at an
operating speed; driving an auxiliary pump via a fan shaft
connected to the auxiliary pump via auxiliary pump gears; pumping
the lubricating liquid with the auxiliary pump from the collection
reservoir to the bearing and collecting the lubricating liquid in
the collection reservoir after use by the bearing, when the high
pressure spool is rotating below the operating speed; and a
compartment wall defining a compartment cavity, wherein the
collection reservoir is positioned at a bottom of the compartment
cavity, wherein a portion of the compartment wall defines the
collection reservoir, and wherein the compartment cavity contains
the auxiliary pump and the bearing.
15. The method of claim 14, and further comprising the step of:
dumping the lubricating liquid pumped by the auxiliary pump to the
collection reservoir prior to lubricating the bearing, when the
high pressure spool is rotating at the operating speed.
16. The method of claim 14, and further comprising the steps of:
collecting the lubricating liquid pumped by the main pump in a
manifold prior to supplying the lubricating liquid to the bearing,
when the high pressure spool is rotating at the operating speed;
and collecting the lubricating liquid pumped by the auxiliary pump
in the manifold prior to supplying the lubricating liquid to the
bearing, when the high pressure spool is rotating below the
operating speed.
17. The method of claim 16, and further comprising the step of:
reducing flow of the lubricating liquid in a direction from the
manifold to the main pump, when the high pressure spool is not
rotating.
18. The method of claim 14, and further comprising the step of:
pumping the lubricating liquid with the auxiliary pump from the
collection reservoir to the bearing and collecting the lubricating
liquid in the collection reservoir after use by the bearing, when
the high pressure spool is not rotating.
19. The method of claim 14, and further comprising the step of:
driving the fan shaft via a low pressure spool connected to the fan
shaft via fan drive gears
Description
BACKGROUND
The present invention relates to pump systems, and more
particularly, to pump systems for lubricating a fan drive gear
system in gas turbine engines.
In many gas turbine engines, a low pressure spool includes a low
pressure turbine connected to and driving a low pressure
compressor, and a high pressure spool includes a high pressure
turbine connected to and driving a high pressure compressor. A main
pump is typically driven by the high pressure spool, connected
through gearing, and is used to pump lubricating liquid to all
engine components that require lubrication. When the high pressure
spool stops rotating or rotates at a reduced rpm (revolutions per
minute), the main supply pump will ordinarily provide little or no
liquid to engine components.
In some gas turbine engines, a fan at the front of the engine is
connected to the low pressure spool through a fan drive gear
system. When the high pressure spool stops rotating or rotates at a
reduced rpm, the fan drive gear system can continue rotating. For
example, wind may rotate the fan and corresponding gears and
bearings while the aircraft is parked on the ground or during an
in-flight engine shutdown. Certain gears and bearings can be
damaged by non-lubricated operation.
SUMMARY
According to the present invention, a pump system for lubricating a
bearing in a gear system includes an auxiliary pump connected to
the gear system. The auxiliary pump is fluidically connected to the
bearing through an auxiliary supply passage and to a reservoir
through an auxiliary scavenge passage. An auxiliary valve is
fluidically connected to the auxiliary supply passage for
transferring liquid from the auxiliary pump to the bearing when a
pressure in the auxiliary supply passage downstream of the
auxiliary valve is less than a particular threshold and for
transferring liquid from the auxiliary pump to the reservoir when
the pressure in the auxiliary supply passage downstream of the
auxiliary valve is greater than the particular threshold. A method
for circulating liquid is also included.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross-sectional side view of a gas turbine
engine with a fan drive gear system.
FIG. 2 is a schematic view of a pump system of the present
invention.
FIG. 3 is a lower cross-sectional view of the fan drive gear system
of FIG. 1.
FIG. 4 is a schematic view of an auxiliary valve of the present
invention.
DETAILED DESCRIPTION
In general, the present invention provides an auxiliary pump for
providing lubricating liquid to bearings of a fan drive gear system
in a gas turbine engine. The auxiliary pump is driven by a fan
shaft and supplements a main pump driven by a high pressure spool.
When the main pump supplies an adequate amount of liquid to the
bearings, a three-way check-valve can use pressure to direct liquid
pumped by the auxiliary pump back to a collection reservoir. When
the main pump supplies less than an adequate amount of liquid, the
three-way check-valve can automatically direct liquid pumped by the
auxiliary pump to the bearings. The auxiliary pump can supply
liquid to the bearings whenever the fan shaft is turning, because
it is connected through gearing to the fan shaft.
FIG. 1 is a schematic cross-sectional side view of gas turbine
engine 10. Gas turbine engine 10 includes low pressure spool 12
(which includes low pressure compressor 14 and low pressure turbine
16 connected by low pressure shaft 18), high pressure spool 20
(which includes high pressure compressor 22 and high pressure
turbine 24 connected by high pressure shaft 26), combustor 28,
nacelle 30, fan 32, fan shaft 34, and fan drive gear system 36
(which includes star gear 38, ring gear 40, and sun gear 42). The
general construction and operation of gas turbine engines is
well-known in the art, and therefore detailed discussion here is
unnecessary. However, a more detailed understanding of fan drive
gear system 36 can be helpful. As shown in FIG. 1, low pressure
spool 12 is coupled to fan shaft 34 via fan drive gear system 36.
Sun gear 42 is attached to and rotates with low pressure shaft 18.
Ring gear 40 is rigidly connected to fan shaft 34 which turns at
the same speed as fan 32. Star gear 38 is coupled between sun gear
42 and ring gear 40 such that star gear 38 revolves around sun gear
42, when sun gear 42 rotates. When low pressure spool 12 rotates,
fan drive gear system 36 causes fan shaft 34 to rotate at a slower
rotational velocity than that of low pressure spool 12.
FIG. 2 is a schematic view of pump system 50 of the present
invention. Pump system 50 includes main pump 52, main supply
passage 54, main check valve 56, manifold 58, bearing supply
passage 60, bearing lubrication distributor 62, main scavenge
passage 64, main scavenge inlet 66, main reservoir 68, auxiliary
pump 70, auxiliary supply passage 72, auxiliary valve 74, auxiliary
scavenge passage 76, auxiliary scavenge inlet 78, fan drive gear
system dump passage 80, auxiliary dump passage 82, and compartment
84 (including compartment wall 86, compartment cavity 88,
compartment bottom 90, collection reservoir 92, and collection
reservoir bottom 94). Compartment wall 86 encloses compartment
cavity 88. Collection reservoir 92 can be part of compartment wall
86, located at compartment bottom 90. Collection reservoir 92 can
have its own collection reservoir bottom 94. In the illustrated
embodiment, substantially all of pump system 50 is located in
compartment 84 except for high pressure spool 20, main pump 52,
main reservoir 68, and portions of main supply passage 54.
Under ordinary operation conditions, main pump 52 supplies
substantially all lubricating liquid necessary for all components
in gas turbine engine 10, including for fan drive gear system 36.
Main pump 52 is a pump for pumping liquid from main reservoir 68 to
main check valve 56. Main pump 52 can be driven by high pressure
spool 20, connected through gearing. Main reservoir 68 is
fluidically connected to main pump 52, which is fluidically
connected to main check valve 56, which is fluidically connected to
manifold 58, all via main supply passage 54. Main reservoir 68
holds a lubricating liquid. Main check valve 56 can allow liquid
flow from main pump 52 to manifold 58 but reduce liquid flow in the
opposite direction. Manifold 58 receives liquid from main supply
passage 54 and directs the liquid through bearing supply passage 60
to bearing lubrication distributor 62. Bearing lubrication
distributor 62 can be a series of passages for distributing the
liquid to star gear 38 (including corresponding journal bearings,
not shown in FIG. 2), ring gear 40, and sun gear 42. Liquid
supplied to fan drive gear system 36 typically drips off each of
the corresponding gears and passes through fan drive gear system
dump passage 80 to collection reservoir 92. Main scavenge passage
64 has main scavenge inlet 66 located in collection reservoir 92.
Main scavenge passage 64 fluidically connects collection reservoir
92 to main reservoir 68 for returning the liquid to main reservoir
68. Liquid in main reservoir 68 can then be pumped back through the
system again.
Auxiliary pump 70 can also supply substantially all lubricating
liquid necessary for fan drive gear system 36. Auxiliary pump 70 is
a pump for pumping liquid from collection reservoir 92 to auxiliary
valve 74. Auxiliary pump 70 can be driven by fan shaft 34,
connected through gearing, such that pump 70 turns whenever fan
shaft 34 turns. Auxiliary pump 70 is fluidically connected to
collection reservoir 92 via auxiliary scavenge passage 76.
Auxiliary scavenge passage 76 has auxiliary scavenge inlet 78
located in collection reservoir 92 and near collection reservoir
bottom 94. Auxiliary scavenge inlet 78 is closer to collection
reservoir bottom 94 than main scavenge inlet 66 is to collection
reservoir bottom 94. This configuration allows a quantity of liquid
to remain in collection reservoir 92 for use by auxiliary pump 70,
as opposed to being scavenged to main reservoir 68. Auxiliary pump
70 is fluidically connected to auxiliary valve 74 via auxiliary
supply passage 72. Auxiliary valve 74 is a three way valve,
fluidically connected to manifold 58 via auxiliary supply passage
72 and to collection reservoir 92 via auxiliary valve dump passage
82. When pressure in manifold 58 exceeds a pressure threshold,
auxiliary valve 74 directs liquid from auxiliary pump 70 through
auxiliary valve dump passage 82 to collection reservoir 92. When
pressure in manifold 58 is below the pressure threshold, auxiliary
valve 74 directs liquid from auxiliary pump 70 to manifold 58.
Liquid in manifold 58 can then be supplied to fan drive gear system
36 in the same manner as described with respect to main pump 52,
above.
Under ordinary operating conditions, high pressure spool 20 will
operate at ordinary operating speed, main pump 52 will supply
liquid to manifold 58, and pressure in manifold 58 will be above
the pressure threshold. Consequently, auxiliary valve 74 will
direct liquid from auxiliary pump 70 to collection reservoir 92.
Under certain conditions, main pump 52 will not supply enough
liquid to manifold 58 to keep pressure in manifold 58 above the
pressure threshold. For example, if high pressure spool 20 stops
rotating or rotates at a reduced revolutions per minute (rpm), main
pump 52 will also stop rotating or rotate at a reduced rpm. Even if
high pressure spool 20 stops rotating, auxiliary pump 70 can
continue pumping liquid so long as fan drive gear system 36
continues rotating. Because of the pressure drop in manifold 58,
auxiliary valve 74 will direct liquid from auxiliary pump 70 to
manifold 58 and, ultimately, to fan drive gear system 36.
Consequently, fan drive gear system 36 can be supplied with
lubricating liquid whenever it is rotating, even when main pump 52
fails to supply such liquid.
In certain embodiments, pump system 50 can contain one or more
conditioning devices to clean and cool the lubricating liquid.
These devices can include filters to clean the liquid, heat
exchangers to cool the liquid, and valves to increase flow and
pressure. In one embodiment, a filter and heat exchanger could be
included along supply passage 54. In other embodiments,
conditioning devices can be included virtually anywhere within pump
system 50 without departing from the spirit and scope of the
invention. Such conditioning devices are omitted from FIG. 2 for
clarity.
FIG. 3 is a lower cross-sectional view of fan drive gear system 36
in gas turbine engine 10. In addition to those elements described
with respect to FIG. 2, above, fan drive gear system 36 further
includes bearing 96, having axially extending bearing passage 98,
and radially extending bearing passages 100. Bearing 96 can be a
journal bearing positioned inside of star gear 38. Bearing
lubrication distributor 62 is positioned adjacent to bearing 96 and
is fluidically connected to axially extending bearing passage 98
which is, in turn, fluidically connected to radially extending
bearing passages 100. Liquid from bearing lubrication distributor
62 can be supplied into axially extending bearing passage 98 where
it then passes through radially extending bearing passages 100 in
between bearing 96 and star gear 38. The lubricating liquid forms a
film of lubrication on bearing 96 to support star gear 38 and
reduce friction between an interior surface of star gear 38 and an
exterior surface of bearing 96 as star gear 38 rotates.
As illustrated in FIG. 3, ring gear 40 is rigidly attached to fan
shaft 34 via fan shaft extension 102. Auxiliary pump 70 is
connected to fan shaft extension 102 via auxiliary pump gears 104.
Consequently, auxiliary pump 70 can rotate at a higher rotational
velocity than fan shaft 34 whenever fan shaft 34 rotates.
FIG. 4 is a schematic view of auxiliary valve 74, which includes
valve body 110, valve cavity 112, auxiliary pump port 114, manifold
port 116, reservoir port 118, sleeve 120, valve member 122, valve
stem 124, first end 126, second end 128, manifold disc 130,
reservoir disc 132, and spring 134. Valve body 110 defines valve
cavity 112. Valve body 110 includes three ports. Auxiliary pump
port 114 fluidically connects valve cavity 112 to auxiliary pump 70
(not shown in FIG. 4). Manifold port 116 fluidically connects valve
cavity 112 to manifold 58 (not shown in FIG. 4). Reservoir port 118
fluidically connects valve cavity 112 to collection reservoir 92
(not shown in FIG. 4). In the illustrated embodiment, manifold port
116 has a greater flow area than that of reservoir port 118. A
ratio of flow area of manifold port 116 to flow area of reservoir
port 118 can be selected to bias the position of valve member 122
toward a position where manifold disc 130 does not close or plug
manifold port 116.
Sleeve 120 can be a circular ring fixedly connected to valve body
120. Valve member 122 includes valve stem 124 positioned inside of
sleeve 120. Valve stem 124 can be substantially cylindrical in
shape with first end 126 and second end 128. Valve stem 124 can
slide inside of sleeve 120. Manifold disc 130 can be fixedly
attached to first end 126 and sized to plug manifold port 116.
Reservoir disc 132 can be fixedly attached to second end 128 and
sized to plug reservoir port 118. Valve stem 124 can have a length
such that liquid can flow through reservoir port 118 when manifold
disc 130 plugs manifold port 116, while liquid can flow through
manifold port 116 when reservoir disc 132 plugs reservoir port 118.
In the illustrated embodiment, valve stem 124 passes through
manifold port 116, valve cavity 112, and reservoir port 118. Spring
134 can bias the position of valve member 122 toward a position
where manifold disc 130 does not plug manifold port 116. In the
illustrated embodiment, spring 134 is compressed between sleeve 120
and manifold disc 130.
It will be recognized that the present invention provides numerous
benefits and advantages. For example, pump system 50 can supply
lubricating liquid to fan drive gear system 36 whenever fan 32 is
rotating. This can be useful in a variety of circumstances, such as
when fan 32 rotates due to wind blowing across it but when gas
turbine engine 10 is not operating. This can also be useful when
gas turbine engine 10 is operating but when main pump 52 does not
supply liquid to fan drive gear system 36. Such situations could
occur due to a hose failure or during a safety test that requires
shut down of main pump 52. Pump system 50 can supply the liquid
automatically, without requiring interaction by a pilot.
Moreover, main pump 52 and auxiliary pump 70 can use the same
liquid and much of the same plumbing, thus reducing cost and
overall weight as compared to a heavier, more complex system.
Because of the unique operation of auxiliary valve 74, liquid from
auxiliary pump 70 is not supplied to fan drive gear system 36
during ordinary operating conditions; it is only supplied when
necessary. Consequently, liquid from auxiliary pump 70 need not be
run through filters so long as the liquid is in condition to
lubricate fan drive gear system 36 for the necessary periods.
Additionally, pump system 50 can be relatively simple and reliable,
requiring little or no additional maintenance by airlines.
Although the present invention has been described with reference to
preferred embodiments, workers skilled in the art will recognize
that changes may be made in form and detail without departing from
the spirit and scope of the invention. For example, auxiliary pump
70 can be connected to any part of fan shaft 34, low pressure spool
12, or fan drive gear system 36 so long as auxiliary pump 70
rotates whenever fan drive gear system 36 rotates.
* * * * *